The shredding of old vehicles for breaking down materials has been known for a long time. In carrying out the shredding method, method controls have been established in which the material mixture produced is divided up into different fractions. Thus, a so-called shredder light fraction (SLF) is initially separated from the material mixture produced, using a suitable suction device. The remaining fraction is subsequently separated into a ferromagnetic fraction (shredder scrap (SS)) and a non-ferromagnetic fraction (shredder heavy fraction (SSF)), using a permanent-magnet separator. The portion of the shredder scrap-metal fraction that is metallurgically fully usable is often approximately 50 to 75 wt. %. Conventional designs generally provide for the shredder light fraction being disposed of as waste or burned in waste incinerators. It is characterized by both a large fraction of organics and a large fraction of fine-grained material. The heavy fraction, which is not able to fly and is not ferromagnetic, i.e., the shredder heavy fraction, is distinguished by a large percentage of nonferrous (NF) metals. Special sorting systems have been developed for recovering the different NF metals, where, however, the remaining residue of organic and inorganic, non-metallic components is generally disposed of as waste. In the following, shredder residues should be understood as all material streams from the shredding process, which cannot be directly removed at the shredder as products that are metallurgically directly utilizable (shredder scrap).
Described in German Published Patent Application No. 44 37 852 is a method, in which the shredder light fraction is sorted to remove “unwanted components”, in particular copper and glass. In this context, the shredder residues are homogenized and mixed in a compulsory mixer with a fine-grained to superfine-grained material containing a magnetizable component, and the resulting mixture is conveyed through a magnetic separator. In this context, it has been shown that the metallic components of the shredder light fraction, which impede metallurgical use, may be separated out in this manner.
European Published Patent Application No. 0 863 114 provides for the production of a permanently plastic, backfilling material for mines, in that an adhesive component, a filler, and a salt solution are added to the shredder light fraction. This is intended to provide a pressure-resistant, permanently plastic body.
It is described in German Published Patent Application No. 197 42 214 that the shredder light fraction is shredded further and subjected to a thermal treatment. In this context, metallic components should be sorted out during or after shredding, and the remaining mixture of materials should be melted in a smelting reactor and converted to a “harmless” solid by cooling it.
In addition, European Published Patent Application No. 0 922 749 describes a method for processing the shredder light fraction, where the shredder light fraction is a calcined in a fluidized-bed gasifier amid the introduction of calcium carbonate.
In a further, thermal process, German Published Patent Application No. 197 31 874 provides for the shredder light fraction being compressed again in a further step, and then shredded, homogenized, and reduced in water content, in order to be thermally utilized in a subsequent step.
European Published Patent Application No. 0 884 107 provides for the shredder light fraction being converted into a metal-free fraction having a shredding size of ≦20 mm, by shredding, classifying, and sorting it. The sorting of the shredder light fraction should result in a thermally utilizable fraction.
In addition to the utilization methods shown, it is conventional that the shredder light fraction can be subjected to a pretreatment, in which residual ferromagnetic fractions of iron, stainless steel, and aluminum are separated. Similar methods have also been used for sorting the shredder heavy fraction. Furthermore, it is conventional that polyolefins can be separated from this fraction.
In addition, it is conventional that plastic granulates can be purified by washing off the dust adhering to the surface, and that the washed granulate can be dried again. Methods in which a granulate mixture of different plastics is split up with the aid of electrostatic separators are also conventional. In this context, differences in the specific capability of the surfaces of the individual plastic materials of being electrically charged are utilized. In particular, halogen-containing granulates such as PVC granulates can be separated from halogen-free granulates in this manner.
What the methods described above have in common is, that they are each only designed for processing the shredder light fraction, the shredder heavy fraction, or an impure granulate from other sources. Common processing with the objective of separating the shredder residues into at least partially utilizable end products to the greatest extent possible, in particular granulate fractions utilizable as raw materials, is not provided. Against the background of increasing legal requirements (EU End of Life Vehicles Directive, EU Directive on Incineration of Waste, and others), as well as increasing landfill costs and requirements for the material to be landfilled, a higher utilization rate is, however, desirable. Thus, the German regulation on end of life vehicles of Apr. 1, 1998 provides for over 95 wt. % of a scrapped car having to be utilized as of the year 2015. In addition, increased requirements from the EU Scrapped Car Guideline passed in September, 2000 specify that the fraction of material streams utilizable as materials and raw materials for mechanical and feedstock recycling should be increased to at least 85 wt. %. Therefore, utilization excludes the use as energy only, e.g., in waste incinerators. For the produced granulate fraction to be able to be used as a raw material in a blast furnace process, in the form of a reducing agent, it must be ensured, in particular, that disruptive heavy metals and chlorine-containing granulates are removed to the greatest possible extent.
It is an object of the present invention to provide a method and the system necessary for it, by which shredder residues may be processed, and by which, in addition to further end products, in particular at least one high-quality granulate fraction usable as a raw material may be produced in a mechanical sorting process.